Pair dispersion in dilute suspension of active swimmers.
J Chem Phys
; 150(6): 064907, 2019 Feb 14.
Article
en En
| MEDLINE
| ID: mdl-30770005
ABSTRACT
Ensembles of biological and artificial microswimmers produce long-range velocity fields with strong nonequilibrium fluctuations, which result in a dramatic increase in diffusivity of embedded particles (tracers). While such enhanced diffusivity may point to enhanced mixing of the fluid, a rigorous quantification of the mixing efficiency requires analysis of pair dispersion of tracers, rather than simple one-particle diffusivity. Here, we calculate analytically the scale-dependent coefficient of relative diffusivity of passive tracers embedded in a dilute suspension of run-and-tumble microswimmers. Although each tracer is subject to strong fluctuations resulting in large absolute diffusivity, the small-scale relative dispersion is suppressed due to the correlations in fluid velocity which are relevant when the inter-tracer separation is below the persistence length of the swimmer's motion. Our results suggest that the reorientation of swimming direction plays an important role in biological mixing and should be accounted in the design of potential active matter devices capable of effective fluid mixing at microscale.
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Bases de datos:
MEDLINE
Asunto principal:
Suspensiones
/
Difusión
Idioma:
En
Revista:
J Chem Phys
Año:
2019
Tipo del documento:
Article
País de afiliación:
Estados Unidos